To develop a national system for occupational mortality, IRS information on occupation is being studied as a possible addition to the Continuous Work History Sample (CWHS) maintained by the SSA, and cause of death will be added to the CWHS file. Through the NIH Census/NDI Working Group efforts are being made to match a sample of the general population against the National Death Index (NDI) to create mortality rates by occupation and industry, not now available in the national mortality data. A mesothelioma study has been started to test the value of SSA files for epidemiologic research. Access by epidemiologists to the IRS address file is being sought through legislation.